@buffalosauce: You’re focusing too much on the sex, ironically. It’s not about having sex for him as it is about being the special first love of her life. Surely you’ve at least seen one story where there were multiple love interests, but the MC chose one over the other because they met first. And of course it’s not about literally being first, but of that bond between people who truly love each other that can’t be interfered with by others, even by other people they could have also loved just as much, and that’s from the simple fact that they have no reason to look at anyone else apart from their first love.
And also not having to compare himself with other men. On the lower end of the bar, that means dick size and sexual prowess, and on the other end, it also means satisfying her in other respects. That’s why MC was wavering in the previous chapter, because he saw someone truly satisfy Mika, making her happier than even who she was when she was with him in the original timeline.
And yeah. You’re being an idiot because of how preoccupied you are with the idea that he’s a disgusting loser for wanting to be Mika’s first sexual partner. Setting aside his desire to have sex with her first, he’s also just genuinely trying to woo her. It’s like you’re expecting him to just ignore her when he knows she’s had a long and troubled romantic history, or that he should only pursue her romantically after she’s already had other relationships. He wants to romance her because he loves her and he also wants to protect her from all the bad end ripple time effects that are happening from this time travel stuff. And you’re just focusing down on it being terrible that he wants to be her first sex partner while ignoring all that. That’s just tunnel vision.